Conventionally, there is known a hybrid vehicle that includes an engine and a motor as power sources, an engine control module that controls an operation and a stop of the engine, and an accelerator pedal to increase or decrease a propulsion force of the vehicle (for example, refer to Patent Document 1). In the vehicle, the engine is started when an output change of the accelerator pedal becomes equal to or larger than a predetermined value within a predetermined period while the motor is only used as the power source, and an output of the motor is decreased in accordance with an increase of an output of the engine after the start of the engine. Further, there is known a power output apparatus for a hybrid vehicle that sets a target rotational speed and a target torque of an engine through the use of an operation curve for a battery limitation state when a state of the battery is not in a state of an allowable input and output range and controls the engine and two motors based on the set target rotational speed and the set target torque (for example, refer to Patent Document 2). In the operation curve for the battery limitation state, high rotation speeds are preset in a low power side in comparison with a normal operation curve so that a rotational speed change with respect to a power change becomes small in comparison with the normal operation curve. Furthermore, there is known a control apparatus of a hybrid vehicle electronically controls operation states of an engine and a motor as power sources for driving the vehicle in accordance with an operation amount of an accelerator by a driver (for example, refer to Patent Document 3). The control apparatus controls the motor to implement a torque assist so as to make a torque increase of the motor higher priority than an output change of the engine. Further, there is known a hybrid electric vehicle that drives a motor by electric power from a battery that is previously charged by a charge source and the like prior to a start of a driving so that a state of charge becomes 100% (for example, refer to Patent Document 4). In the hybrid electric vehicle, when the state of charge becomes 50% after the start of the driving, a prime mover is driven to start a power generation by a generator, so that electric power is supplied to the motor of the vehicle and is used to charge the battery. An operation of the prime mover and the power generation by the generator are stopped when the state of charge becomes 55%. Then, the motor is driven by only electric power from the battery.    [Patent Document 1] Japanese Patent Laid-Open No. 2003-343304    [Patent Document 2] Japanese Patent Laid-Open No. 2006-077600    [Patent Document 3] Japanese Patent Laid-Open No. Hei 10-23608    [Patent Document 4] “Background Art” of Japanese Patent Laid-Open No. Hei 09-98517